SHO Factor based on DT Analysis 1 Definition of SHO Factor based on DT

According to the DT data from scanner, you can obtain the SHO Factor based on DT, defined as below:

 DTin points collected-scanner totalofNumber conditionshandover meet the that DTin points collected-scanner ofNumber ＝RatioHandoverSoft

 No subscribers are using the network during RF optimization stage, so UE DT data of entire network in a time is used and geographically averaged by 5 meters. You can obtain the ratio of the points in soft handover state to all DT points. Set the scanner consistent to the system parameters with default configuration, such as 1A and 1B threshold.

7.2.2 General Principles and Methods in Optimization

The SHO Factor based on DT during RF optimization stage must be 5%–10%2 lower than the KPI target value, because the following optimizations cause SHO Factor based on DT to increase and brings difficulties in ensuring traffic measurement SHO Factor based on DT.

At the end of large-scale coverage optimization and pilot pollution optimization, the SHO Factor based on DT will be within or close to the target range. Upon this, no specific optimization on SHO Factor based on DT is necessary, and you can adjust the ratio during parameter optimization. If the SHO Factor based on DT still cannot meet the requirements after large-scale adjustment, you must optimize the SHO Factor based on DT.

If the SHO Factor based on DT is over large, decrease or change the handover areas by using the following methods for shrinking coverage areas:

 Increase the down tilt  Adjust azimuth

 Decrease the antenna height  Decrease the PICH power

The precondition for adjustment is that the adjustment will not cause new coverage voids, coverage blind zone, and more pilot pollution. The adjustment proceeds as below:

 Start post processing software

 Analyze scanner-based RSCP for 4th Best ServiceCell and RSCP for 3rd Best ServiceCell

 Select candidate cells in the 4th Best ServiceCell and 3rd Best ServiceCell 0 shows the RSCP for the candidates in 4th Best ServiceCell. List the SC136 cell as a candidate cell. At this stage, the pilot pollution comes to an end. RSCP for 3rd Best ServiceCell is more useful in terms of reference.

 Select the sites or cells to which the adjustment is applicable and does not break the preconditions. If the actual SHO Factor based on DT after adjustment is still different from the KPI one, select candidate cells from RSCP for 2nd Best ServiceCell. The sites are densely distributed in microcell coverage areas, so the SHO Factor based on DT is much higher.

RSCP for candidate of 4th Best ServiceCell

8 Adjustment Methods

The adjustment during RF optimization stage include adjusting neighbor cell list and adjusting engineering parameters.

Most coverage and interference problems can be solved after adjusting the following site engineering parameters (from superior to inferior):

Adjust antenna down tilt Adjust antenna azimuth Adjust antenna height Adjust antenna location Change antenna type Add TMAs

Change site type (such as changing a site supporting 20 W power amplifier to a site supporting 40 W power amplifier)

Change site location

Construct new site or add RRU

9 Summary

This document describes the content of RF optimization in network optimization. RF optimization concern the improvement of signal distribution, and it helps to provide a good radio signal environment for the following parameter optimization.

The test during RF optimization is usually DT, with other tests as supplementary. The problems to be analyzed during RF optimization is primarily about coverage, pilot pollution, and handover, with problem as supplementary. RF optimization help to solve handover, call drop, access, and interference problems. The parameters to be adjusted during RF optimization are primarily engineering parameters. Cell parameters are adjusted during parameter optimization stage (excluding adjusting neighbor cell list).

This document is mainly for RF optimization of new network. How to optimize an existing network for expansion needs further tracing. The methods for optimize SHO Factor based on DT and the judgment conditions for removing neighbor cells are still under research, and they will be supplemented in the future versions.

10 Appendix: Coverage Enhancement Technologies 10.1 Coverage-enhancing Technologies

10.1.1 TMAs

Using TMAs helps to reduce the total noise figure of NodeB receiver subsystem, so the uplink coverage performance is improved. The coverage gain depends on the mechanism of receiver subsystem and loss of related feeders. If the system downlink capacity is restricted, using TMAs will shrink system capacity. The typical capacity shrinkage is 6%–10%.

10.1.2 Receive and Transmit Diversity

Increase the number and improve the quality of RAKE receivers of UE by using time switched transmit diversity (TSTD) and space and time transmit diversity (STTD) in the downlink. Therefore the coverage range is expanded, system capacity increases, and the number of NodeBs decreases.

Using four-antenna receiver diversity reduces requirements on Eb/No needed in demodulation. In line of sight, compared with the gains of 2 antennas with 2 receiver diversity, the gain of 2 antennas with 4 receiver diversity is 2.5–3.0 dB. You can adjust the uplink sensitivity by 2.5–3.0 dB and reduce the sites by 25%–30%.

10.1.3 RRU

Remote radio unit (RRU) physically detach NodeB RF module from baseband module, so you can place RF module afar without using very long feeders. The uplink and downlink link budget is improved. Remote RF indicates that the coverage performance is improved but the system capacity remains the same. Compared with remote RF, using TMAs increases maximum path loss and lowers NodeB EIRP due to bringing insertion loss.

10.1.4 Micro Cells

NodeBs are densely distributed in urban and dense urban areas, so selecting a site is difficult. Using micro cells is a solution to high capacity and caters for urban and dense urban environment. A feature of using micro cells is that buildings are

used to block signals so that the interference from neighbor cells is lowered and downlink capacity is increased.